An imaging apparatus that contains an imaging sensor and captures a subject to generate image data has become noticeably common. As such an imaging apparatus, an imaging apparatus in which an optical system and a body is integrated has become common. However, high quality image data requires more, and an imaging apparatus in which an optical system can be separated from a body has also started to become widespread.
An original imaging apparatus in which the optical system can be separated from the body is a film type single-lens reflex camera. An imaging apparatus having an image sensor instead of the film is a digital single-lens reflex camera. As generally known, the body of the digital single-lens reflex camera is provided with a movable mirror similarly to the film type single-lens reflex camera. The movable mirror is normally arranged on an optical path of subject light incident via an interchangeable lens and guides the subject light to an optical finder. The movable mirror leaves the optical path so as to lead the subject light to the imaging sensor only at the time of shooting an image. Therefore, in the digital single-lens reflex camera, a user observes subjects via the optical finder and determines composition.
A user, who has used a so-called compact digital camera of which an optical system and a body are integral, is used to determining composition while observing a large-size liquid crystal display monitor provided on a rear surface of the body. Such a user is frequently not used to the optical finder to be viewed.
Therefore, a digital single-lens reflex camera having the movable mirror arranged in the body has emerged. In the camera, the movable mirror is allowed to leave the optical path so that subject image can be displayed on the large-size liquid crystal display monitor provided on the rear surface of the body even in cases other than shooting an image. A function for displaying subject image on the large-size liquid crystal display monitor provided on the rear surface of the body is occasionally referred to as “a live view function”.
However, the digital single-lens reflex camera adopts a normally closed shutter that is open only at the time of shooting an image. Therefore, the normally closed shutter should be maintained opened in order to realize the live view function, thus resulting in large power consumption.
Therefore, a digital single-lens camera that does not have the movable mirror in a body and adopts a normally open shutter has emerged. Hereinafter such a digital single-lens camera is referred to as “a digital single-lens camera”, in which “reflex” meaning an reflex mirror is eliminated in order to discriminate it from the digital single-lens reflex camera having the movable mirror. With the digital single-lens camera, subject can be always observed through the large-size liquid crystal display monitor provided on the rear surface of the body similarly to the compact digital camera. Since the digital single-lens camera is not provided with the movable mirror, the digital single-lens camera cannot be provided with the optical finder in the body. In the daytime outside, observation of a subject via the liquid crystal display monitors provided on the rear surface of the body is occasionally obstructed. In case of such a situation, the digital single-lens camera is sometimes provided with a looking-through type electronic finder. Since the digital single-lens camera does not have the movable mirror, the body can be extremely miniaturized. Further, since the normally open shutter can maintain the opened state if power is not supplied thereto, the power consumption is reduced.
Patent Documents 1 and 2 disclose digital single-lens reflex cameras having the live view function.